text: #ifdef HAVE_CONFIG_H
  #include <../../nrnconf.h>
  #endif
  /*
  Based on Unidraw UList but UList changed to HTList (head tail list)
  for fast insertion, deletion, iteration
  */
  
  /*
   * Copyright (c) 1990, 1991 Stanford University
   *
   * Permission to use, copy, modify, distribute, and sell this software and its
   * documentation for any purpose is hereby granted without fee, provided
   * that the above copyright notice appear in all copies and that both that
   * copyright notice and this permission notice appear in supporting
   * documentation, and that the name of Stanford not be used in advertising or
   * publicity pertaining to distribution of the software without specific,
   * written prior permission.  Stanford makes no representations about
   * the suitability of this software for any purpose.  It is provided "as is"
   * without express or implied warranty.
   *
   * STANFORD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
   * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
   * IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
   * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
   * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
   * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
   * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  /*
   * HTList implementation.
   */
  
  #include <stdio.h>
  #include <OS/enter-scope.h>
  #include <htlist.h>
  
  /*****************************************************************************/
  
  HTList::HTList (void* p) { _next = this; _prev = this; _object = p; }
  
  HTList::~HTList () {
      HTList* next = _next;
      if (next != this && next != NULL) {
          Remove(this);
          delete next;
      }
  }
  
  void HTList::Append (HTList* e) {
      _prev->_next = e;
      e->_prev = _prev;
      e->_next = this;
      _prev = e;
  }
  
  void HTList::Prepend (HTList* e) {
      _next->_prev = e;
      e->_prev = this;
      e->_next = _next;
      _next = e;
  }
  
  void HTList::Remove (HTList* e) {
      e->_prev->_next = e->_next;
      e->_next->_prev = e->_prev;
      e->_prev = e->_next = NULL;
  }
  
  void HTList::Remove() {
  	if (_prev) { _prev->_next = _next; }
  	if (_next) { _next->_prev = _prev; }
  	_prev = _next = NULL;
  }
  void HTList::RemoveAll() {
  	while(!IsEmpty()) {
  		Remove(First());
  	}
  }
  void HTList::Delete (void* p) {
      HTList* e;
  
      e = Find(p);
      if (e != NULL) {
  	Remove(e);
  	delete e;
      }
  }
  
  HTList* HTList::Find (void* p) {
      HTList* e;
  
      for (e = _next; e != this; e = e->_next) {
  	if (e->_object == p) {
  	    return e;
  	}
      }
      return NULL;
  }
  
  HTList* HTList::operator[] (int count) {
      HTList* pos = First();
      int i;
  
      for (i = 1; i < count && pos != End(); ++i) {
  	pos = pos->Next();
      }
      if (i == count) {
  	return pos;
      }
      return NULL;
  }	
  